The present invention relates to sensing the shape of the wavefront of visible and invisible light rays and, in particular, for directly sensing the curvature of the wavefront for use in various applications.
There are various methods and devices for sensing the wavefront of light waves for then measuring and/or correcting aberrations in the wavefront that are sensed by the device. The existing methods and devices of sensing and measurement include several interferometric techniques, the Shack-Hartmann wavefront sensing techniques and various other systems involving the projection of patterns of light through an optical system. Such prior techniques and systems are typically complex and expensive, as well as having various inherent deficiencies. For example, many such systems and techniques require access to the focal plane of the optical system being tested for sensing the wavefront which is not possible in many applications, such as for measuring the optical aberrations of the lens system of the human eye because the focal plane is inside the eyeball. While the Shack-Hartmann wavefront sensor does not require access to the focal plane, whereby it may be used for measuring the optical aberrations of the human eye for example, such sensor has numerous other deficiencies. The Shack-Hartmann wavefront sensor measures the gradient of the wavefront rather than directly measuring the curvature of the wavefront, which is not completely accurate for some applications and impairs the speed of any corrective adaptive optics procedures that may be taken in applications requiring high speed corrections. Also, the Shack-Hartmann system uses an array of light detectors that senses the position of a single image whereby any gain or bias in individual detectors produce a false result. The Shack-Hartmann device requires periodic calibration. Further, the Shack-Hartmann system doesn""t respond correctly to extend objects, such as plural point sources of light, for the most common implementations. Some other wavefront sensing techniques and devices are not directly applicable to adaptive optics techniques for correcting the wavefront to thereby correct the image, such as used in celestial telescopes for correcting aberrations caused by continual changes in the atmosphere that adversely affect the seeing of the telescope.
It is an object of the present invention to provide a novel wavefront sensing device and method that uses defocused pupil images for sensing the curvature of the wavefront of light waves for any desired application of the wavefront data and/or pupil images. A further object of this invention is to provide such a wavefront sensor that employs optical means for producing at least one defocused pupil image on a detector and means for processing that defocused pupil image to determine the curvature of the wavefront of the light waves received by the optical means. A still further object of this invention is to provide such a wavefront sensor wherein the optical means produces two defocused pupil images on a detector means wherein the two defocused pupil images thereof are located at equal distances in front of and behind the object image plane for the processing means to compare equally defocused pupil images in determining the curvature of the wavefront.